Tooth whitening or stain removing agents are known to be added to dentifrice compositions such as toothpaste, mouthwash, chewing gum, confectionary compositions and the like. The use of such compositions for reducing stains and discolouration of tooth surfaces thereby improving the general cosmetic appearance of the teeth is likewise well-known. Teeth with extrinsic stains are objectionable both on the basis of cosmetic appearance and also socially as indication of poor oral hygiene.
Some products contain peroxides, but these are, however, problematic from a toxicological point of view. Another approach to tooth whitening products is to add abrasives—known mainly from dentifrices. Not all of these are legal in confectionary. Further, a significant tooth whitening effect would not be expected to occur following the consumption of confectionary compositions comprising abrasives as these compositions are not suitable for continuous chewing.
Several abrasive agents have been used for tooth whitening purposes and these are known to the person skilled in the art. Examples of abrasive agents include calcium carbonate, sodium bicarbonate, sodium metaphosphate, potassium metaphosphate, tricalcium phosphate, dihydrated dicalcium phosphate, calcium pyrophosphate, bentonite, zirconium silicate or other siliceous materials. Other suitable abrasives are described in U.S. Pat. No. 4,170,633 and U.S. Pat. No. 4,891,211, incorporated herein by reference.
Several patents and patent applications disclose the use of abrasive materials in solid, oral compositions, see for example U.S. Pat. Nos. 5,147,632 and 5,496,541, EP Patent No. 372,603, International Publication Nos. WO 02/19834 and WO 01/56399.
US Patent Application US 2002/0142068 discloses chewing gum formulations including sodium pyrophosphate and encapsulated aspartame.
U.S. Pat. No. 4,233,288 discloses a gum emulsified liquid composition for delivering and preserving the liquid content in the mouth. The herein disclosed examples describe a gum emulsified liquid composition comprising 5% of calcium pyrophosphate and more than 50% of liquid components.
U.S. Pat. No. 3,590,120 discloses a chewing gum comprising a polishing agent comprising a mixture of fine and coarse zirconium silicate particles. Disclosed herein are reference chewing gum compositions containing 10% of calcium pyrophosphate or 10% of calcium carbonate, respectively. The cleaning/polishing effects of said compositions are shown to decrease in the order ZrSiO4, CaCO3 and CaP2O7. Indicative studies have however shown some problematic toxicological properties of zirconium silicate (Elmore AR, Cosmetic Ingredient Review Expert Panel, Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminium silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite, Int. J Toxicol. 2003; 22 Suppl. 1:37-102) and the use of zirconium compounds in solid oral compositions is prohibited in a number of countries.
Thus, a need exists in the art to identify and use abrasives in solid, oral tooth whitening compositions, to obtain an increased whitening effect, which compositions are safe and convenient to administer and apply.